orionids Archives

October 19, 2015December 23, 2015 by David Dickinson

The 2015 Orionids: Watch the Meteors Fly from the Club of Orion

(Note: we’ll be posting this article as a running blog with updates over the next few mornings, as the Orionids are already moderately active for this week. Watch this space for info as it is added after our first meteor vigil tomorrow morning and Wednesday, weather and clear skies willing…)

The month of October is about midway through meteor shower season for the northern hemisphere, and one of the annual sure-fire best bets is the Orionid meteor shower. One of two meteor showers emanating from debris shed by that most famous of all periodic comets –1/P Halley—the Orionids generate a typical zenithal hourly rate of around 20 per hour, though surges heading towards a ZHR of in the range 70 are not unknown on some years.

Orionid radiant — The radiant for the Orionid meteors, looking eastward around 2 AM local. Image credit: Stellarium

2015 sees the shower peaking right around the morning of Wednesday, October 21^st. This will place the Moon at a 59% illuminated waxing gibbous phase and setting around local midnight, setting the stage for dark AM skies, perfect for meteor hunting.

Like the springtime Eta Aquarids also generated by Halley’s Comet, the Orionids are swift movers, striking the atmosphere at about 66 kilometers per second. The shower’s radiant drifts across the club of Orion the Hunter toward the astronomical constellation Gemini near its peak, and the radiant rides highest around 4 AM local time. This is also typically the best time to carry out a meteor vigil, as early morning hours places an Earth-bound observer facing forward into the oncoming meteor stream.

The twin Spring and Fall showers hailing from Halley’s are a product of the geometry of its elliptical orbit: Halley’s Comet spends most of its 75.3 year orbit south of the ecliptic, and only briefly ‘pops up’ northward above the Earth’s orbit for northern hemisphere viewers for a few months around perihelion, which next occurs on July 28th, 2061.

Let’s see, I’ll be 90-something next time Halley’s Comet comes ‘round next…

Like many meteor showers, researchers (with the tongue-twisting title of meteoriticists) are still working to precisely model the debris streams of showers such as the Orionids. There’s evidence to suggest an 11 year periodicity for the Orionid meteor stream undergoing modification by the gravitational influence of the giant planet Jupiter, a period which we’re approximately passing the mid-point low for in 2015.

Rates for the Orionids from previous years seem to support this trend: over the last few years, observers saw the Orionids top out at a ZHR of 21(2014), 45(2012), 33(2011) and 38(2010) as per the International Meteor Organization (IMO).

The next few mornings are key for a successful Orionid vigil. The Orionids also display a broad swath of activity, typically running from early October, to the first week of November before falling back down to levels below the background sporadic rate.

And while 2015 may be an off year for the Orionids, another shower may prompt a once a decade fireball swarm to rival the Full Moon this Halloween right into early November…

Will the Northern Taurids of 2015 perform? Stay tuned!

Update: Well, skies were indeed clear over the Central Florida peninsula this AM, allowing for a brief one hour vigil before dawn ensued. We counted three swift Orionids for about 40 minutes of total effective observing time, suggesting the the current rate is already well above the background sporadic rate, not bad. A late season Draconid meteor, and a curious unidentified tumbling satellite on a retrograde (read ‘Earth observing’ or spy satellite) orbit also joined the fray, along with the current cavalcade of dawn planets. A nice pass of the Hubble Space Telescope capped off the session as dawn broke, not bad.

The Orionids are noticeably speedy, flitting briefly in and out of view. Another great plus with this shower: The radiant is almost directly at the zenith for Florida residents at around 5 AM or so. This means that the Orionids can be enjoyed fairly far southward as well… has anyone ever studied just why a majority of major meteor shower radiants reside in the northern hemisphere?

The IMO hasn’t yet put up their live tracker yet, but hey, you can still report those Orionid rates worldwide…. We’ll see what Wednesday and Thursday morning brings as the Orionid meteor peak arrives. Unlike many showers, the Orionids have a very broad peak, and should be active all week into late October.

And don’t forget the tweet those sightings to #Meteorwatch!

October 22, 2014December 23, 2015 by Bob King

Beastly Sunspot Amazes, Heightens Eclipse Excitement

Ron Cottrell captured the sunspot in all its swirly magnetic goodness in hydrogen-alpha light on October 19. To appreciate its size, he included the Earth (lower left) for reference. Credit: Ron Cottrell

That’s one big, black blemish on the Sun today! Rarely have we been witness to such an enormous sunspot. Lifting the #14 welder’s glass to my eyes this morning I about jumped back and bumped into the garage.

Properly shielded, it was very easy to see with the naked eye. Unlike some other naked eye sunspots, this one showed structure. The eastern end was darker, the western half grayer and more extended.

Watch the giant spot rotate into view and grow right before your eyes in this 72-hour time-lapse video taken by SOHO’s HMI imager Oct. 18-20, 2014

Through a small telescope, the mix of dark umbras scattered amid weirdly sculpted penumbral “islands” was incredible to see. Photographs like the one above are wonderful documents, but witnessing this beautiful complex magnetic mess with your own eyes is another experience altogether. Region 2192 continues to grow and size and complexity and is now the largest sunspot group of solar cycle 24 which began in 2009 – more than five years ago!

Active region 2192 is now the largest sunspot group to appear in over five years. Credit: Alex Young — Active region 2192 is now the largest sunspot group to appear in over five years. Compare to Jupiter and the Earth. Credit: SDO/HMI/Alex Young

Every sunspot marks a region on the Sun’s shiny outer skin called the photosphere where magnetic energy is concentrated. Strong magnetic fields within a sunspot group quell the turbulent churning of the photosphere, chilling the region by several thousand degrees. Sunspots appear dark against the Sun’s blazing disk because they’re cooler. Cooler meaning 8,000 F instead of 11,000 F, so yes, they’re still VERY hot.

Watch as Region 2192 crackles with energy and flares as seen in far ultraviolet light with NASA’s Solar Dynamics Observatory.

Energy stored in sunspots’ twisted magnetic fields can suddenly be released in violent, explosions called solar flares. Billions of tons of solar plasma – the sizzling mix of protons and electrons that composes the Sun – are heated to millions of degrees during the explosion and rapidly accelerated into space. Radiation from radio waves to X-rays and gamma rays fans out at the speed of light. Fortunately for us, our atmosphere and planetary magnetic field protect us from most of what flares can fling our way.

NASA's Solar Dynamics Observatory took this photo of the sun and Jupiter-sized sunspot 2192 this morning Oct. 22 at 8:45 a.m. CDT. The view in a small telescope equipped with a safe solar filter is even better! Credit: NASA — NASA’s Solar Dynamics Observatory took this photo of the Sun and Jupiter-sized sunspot region 2192 this morning Oct. 22 at 8:45 a.m. CDT. The view in a small telescope equipped with a safe solar filter is even better! Credit: NASA

But as the Sun rotates this monster into our line of sight, possibilities for Earth-directed flares and coronal mass ejections increase as do geomagnetic storms, the bringer of auroras. Already in the past 48 hours, the spot has dished out seven M-class flares and a powerful X-1 flare even before it has fully come into view. There’s more to come – Region 2192 harbors an unstable beta-gamma-delta magnetic field ripe for additional flaring including more of the X-class variety.

The sun on October 21 showing smaller sunspot regions along with our featured group. Credit: Sarah and Simon Fisher — The Sun on October 21 showing smaller sunspot regions along with our featured group. Credit: Sarah and Simon Fisher

There’s no doubt now that this behemoth will stick around to add a whole new dimension to tomorrow’s partial solar eclipse. I can’t wait to see the Moon’s black curve approach and at least partially occult the group from view. If you’re interested in getting some one-of-a-kind pictures of the scene, please see our own Dave Dickinson’s excellent guide on photographing the partial eclipse.

A sliver of a Moon rises in morning twilight today October 22 just a day away from its appointment with the Sun. Credit: Bob King

While we’re on the Moon, early morning risers had the pleasure of its company just one day before New Moon and solar eclipse. I was out watching the Orionid meteor shower. While not rich like the Perseids or Geminids I managed to catch a few including a few lucky shots with the camera.

An Orionid meteor slashes across the top of the frame directly above the constellation Orion early this morning October 22, 2014. Details: 24mm lens, f/2.8, 30-seconds at ISO 1600. Credit: Bob King

The shower has peaked but will still be active the remainder of the week if you’re inclined to take a look. And I can’t resist. How about one last sweet close-up photo of sunspot group 2192? I have a feeling you won’t mind.

Monster Sunspot AR12192 taken by Karzaman Ahmad on October 21, 2014 from Langkawi Nagtional Observatory, Malaysia credit: Karzaman Ahmad and shared at spaceweather.com — Monster Sunspot AR12192 taken by Karzaman Ahmad on October 21, 2014, from Langkawi Nagtional Observatory, Malaysia. Credit: Karzaman Ahmad and shared at spaceweather.com. Click the image to see additional animations and photos on Alex Young’s site

October 13, 2014December 23, 2015 by David Dickinson

Get Ready for the Fireballs of October

A recent fireball captured over the UK on October

On October 31^st 2005, trick-or-treaters across the central U.S. eastern seaboard were treated to a brilliant fireball, a celestial spectacle that frequently graces October skies.

Mid- to late October is fireball season, a time when several key meteor showers experience a broad peak. We’re already seeing an uptick in fireball activity as monitored by numerous all-sky cameras this month, including NASA’s system positioned across the United States. Three lesser known but fascinating showers are the chief culprits.

A Bay area fireball captured in 2012. Credit: NASA/Robert P. Moreno Jr.

The main meteor shower on tap for the month of October is the Orionids. This shower radiates from the Club of the constellation Orion, and is the product of that most famous comet of them all, 1P Halley. Halley’s Comet is actually the source of two annual meteor showers, the October Orionids and the May Eta Aquarids. We’re seeing the inward stream of Halley debris in October, and Orionid velocities average a swift 66 kilometres a second. The radiant rides highest for northern hemisphere observers at 4 AM local, and 2014 sees an estimated zenithal hourly rate (ZHR) of 20 predicted to arrive on the mornings of October 21^st through the 22^nd. The Orionids experience a broad peak spanning October 21^st through November 7^th, and 2014 sees the peak arrive just two days prior to the Moon reaching New phase. The Orionids have exhibited an uptick in activity as high as 50-75 per hour from 2005-2007, and it’s been suggested that a 12 year peak cycle may govern the Orionids, as the path of meteoroid debris stream is modified by the gravitational influence of the giant planet Jupiter.

Two other nearby radiants in the sky also produce an exceptionally large number of fireballs in late October: the Southern Taurids and Northern Taurids. These are complex streams laid down by the periodic comet 2P Encke, which possesses the shortest orbital period of any comet known at 3.3 years. Though the ZHR for both is only slightly above the background sporadic rate for northern hemisphere Fall at about five per hour, the Taurids also produce a high ratio of fireballs. The southern Taurids peak in early October and are already active, and the Northern Taurids peak in late October through early November, earning them the nickname the “Fireballs of Halloween”. Unlike many meteor showers, the Northern Taurids are approaching the Earth from behind in our orbit and have a slow relative atmospheric entry velocity of 28 kilometres per second. This makes for long, stately meteor trains often visible in the evening hours before local midnight.

The Taurids also seem to exhibit a seven year periodicity that begs for further study. 2008 was a fine year for Taurid fireballs… could 2015 be next?

Of course, the exact definition of a “fireball” meteor varies by source, though we prefer the definition of a fireball as a meteor brighter than magnitude -3. A fireball reaching -14 (a Full Moon equals magnitude -13, about 2.5 times fainter) is often termed a bolide.

Halley's orbit — Comet 1P/Halley’s orbital path through the inner solar system. (Credit: NASA/JPL).

Observing meteor showers such as the Orionids is as simple as sitting back and patiently watching the skies. Our own personal rule while starting a meteor vigil is to scan the skies for 10 minutes; one or more meteor sightings is a good sign to keep on watching, while no meteors means it’s time to pack it in and instead maybe write about astronomy. Dark, moonless skies are key, and you can report how many meteors you see to the International Meteor Organization. Be sure to keep a pair of binoculars handy to examine any lingering smoke trails post-fireball passage.

The positions of the radiants of the Orionids and the Taurids, with peak dates. Credit: Stellarium.

Of course, seeing a Taurid fireball is largely a matter of luck and looking at the right place in the sky at the right time. All-sky cameras work great in this regard, and many amateurs now use tripod mounted DLSRs set to take wide-field exposures of the sky automatically throughout the night. Just watch out for dew! Nearly every meteor we’ve caught on camera turned up only in post review, a testament to how much of the sky a lone pair of eyes still misses.

Spot a fireball? The American Meteor Society maintains a great online database of recent sightings and reports. Keep in mind, lots of “meteor-wrongs” inevitably crop up on Facebook and Twitter during any event, posted by folks eager for likes and retweets. Faves of such spoofers are: the Peekskill meteor train, the reentry of Hyabusa, Mir, and scenes (!) from the movie Armageddon. We’ve seen ‘em all passed off as legit, though you’re more than welcome to try and be original… a majority of initial meteor images almost always come from dash cams (remember Chelyabinsk?) and security cameras.

Finally, in addition to fireballs, there’s another astronomical tie-in for Halloween, as it’s one of four cross-quarter tie-in days approximately mid-way between a solstice and an equinox. The other three are: Lammas Day (August 1st), Groundhog’s Day (February 2nd) and May Day (May 1^st). We just think that it’s great — if a bit paradoxical — to see modern day suburbanites dress up as ghouls and goblins as they reenact archaic rites and holidays…

Don’t forget to keep an eye out for the fireballs of October this Halloween!